90 Pontederiaceae 
AA.  Thalloid shoots sessile, elliptic-oblong, 2.5—-4 mm. long, soon separating. W. 
E. L. minor L. (Small Duck-weed) 
SPIRODELIA 
Thalloid shoots round-obovate, purplish beneath, 3—8 mm. long, each with a 
cluster of 2-10 rootlets. Roots with central vascular cylinder. Anther-cells vertical. 
Seeds 2. (Gk. speira=a cord, delos=evident; from the thread-like roots.) W. E. 
S. polyrhiza Schl. (Large Duck-weed) 
PONTEDERIACEAE Pickerel-weed Family 
Herbs. Leaves grass-like (ours) or petioled. Flowers solitary (ours) or in spikes, 
subtended by a leaf-like spathe, perfect, mostly irregular. Perianth free from the ovary, 
corolla-like, 6-parted. Stamens 3 (ours) or 6, mostly equal (not in ours), inserted on 
the tube (ours) or base of the perianth; filaments ‘filiform; anthers introrse. Ovary 3- 
celled with the placentae in the axis, or I-celled with 3 parietal placentae; style 1, filr- 
form or columnar; stigma entire or minutely toothed. Fruit a many-seeded capsule 
(ours), or a I-seeded utricle. Jn water or bogs. 
HETERANTHERA MUD-PLANTAIN 
Low; stems creeping or ascending or floating. Flowers small, yellow (ours) or 
white or blue. - Perianth-lobes equal or nearly so, linear; tube thread-like (ours): 
Ovary fusiform; stigma 3-lobed. Capsule ovoid, enclosed in the perianth-tube. (Gk. 
hetera—different, anthera—anther; ours and some other species have 2 forms of anthers.) 
De H. dubia MacM. 
JUNCACEAE Rush Family 
Annual or perennial, grass-like or rush-like. Inflorescence usually compound, pan- 
icle-like or umbel-like or even head-like, rarely a single flower. Flowers small, regular, 
hypogynous, persistent, with or without bractlets. Sepals 3, glumaceous. Petals 3, 
similar to the sepals. Stamens 6 or-rarely 3; anthers 2-celled, introrse. Pistil 3-car- 
pous, either |-celled with 3 parietal placentae, or 3-celled; ovary superior; stigmas 3, 
filiform. Fruit a loculicidal capsule, 3-valved. Seeds 3—-many, small. 
A.  Leaf-sheaths open; leaves never hairy, mostly not flat nor grass-like; capsule 1- 
celled or 3-celled, many-seeded; placentae parietal or axial. Juncus (p. 90) 
AA.  Leaf-sheaths closed; leaves often with few large hairs, flat, grass-like; capsule 
l-celled, 3-seeded; placenta basal. . JUNCOIDES (p. 93) 
JUNCUS RUSH 
Plants glabrous, annual or perennial. Stem pithy or hollow, simple or rarely 
branching, terete or angular, leafless or leafy. Leaves terete or channeled or flat, some- 
times equitant, often with cross-partitions in them. Flowers solitary, or in cymes or 
panicles or heads, greenish or brownish. Stamens 6, or 3 opposite the sepals. Capsule 
3-celled, or I-celled by the placentae not reaching the axis. In water or wet soil. 
(L. jungere—to bind; some species were twisted together for ropes.) 
A. Involucre leaf appearing like a continuation of the stem, erect, terete, not conspic- 
uously channeled, the inflorescence therefore appearing lateral. 
B. Plants usually over 25 cm. high, the smallest species reaching 60 cm., not char- 
acteristically alpine, some species caespitose; flowers in compound panicles, usually 
numerous; stamens 3 or 6. 
